Okay, I think I can get my head around that, it did just take some reading up - does this mean that there'll always need to be a specific relay (or relays) available to initiate the contact between peers, or would they be able to signal each other independently after they initially male contact? 

Sorry for what probably seem like really noob questions, I'm just a bit curious and wondering how far this could go towards not needing a phone number any more. 

 No worries.

Every time you make a voice or video call, you need to use Nostr relays (in this case, your general relays) for signaling communication. 

 Ah okay, is that where the NIP100 bit comes in? If communication can be established over general relays then the app isn't dependent on you guys running specific relays?  

 Yes, exactly! The app doesn't depend on us running specific relays. This gives you the flexibility to use other relays or even set up your own if you prefer.  

 Damn...this is awesome. Truly amazing work. I really can't help but wonder if this would be a way to go about doing away with a phone number all together.